Chapter 11: Substance Abuse

SUBSTANCE ABUSE  Compare the various routes of drug administration  Explain the ways in which drugs can influence the nervous system and how they are eliminated from the body. LEARNING OUTCOME  Describe how the body becomes tolerant to drugs and the process of drug withdrawal. Explain what it means to be physically dependent on a drug.  Define drug addiction.  Understand the 5 commonly used drugs  Compare the direct health hazards of alcohol, tobacco, marijuana, heroin, and cocaine  There are 4 ways on how drugs are administered which is:  Oral Ingestion Drug Administration , Absorption & Penetration of the CNS  The oral route is the preferred route of administration for many drugs  Drugs dissolve in the fluids of the stomach and are carried to the intestine, where they are absorbed into the bloodstream.  Some drugs readily pass through the stomach wall (e.g., alcohol), and these take effect sooner because they do not have to reach the intestine to be absorbed.  Injection  the effects of injected drugs are strong, fast, and predictable.  Drug injections are typically made subcutaneously (SC), into the fatty tissue just beneath the skin; intramuscularly (IM), into the large muscles; or intravenously (IV), directly into veins at points where they run just beneath the skin.  Many drug-addicted persons prefer the intravenous route because the bloodstream delivers the drug directly to the brain. – however, has pros and cons, there is little or no opportunity to counteract the effects of an overdose, an impurity, or an allergic reaction.  Inhalation  Some drugs can be absorbed into the bloodstream through the rich network of capillaries in the lungs.  tobacco and marijuana  Absorption through mucous membranes  Some drugs can be administered through the mucous membranes of the nose, mouth, and rectum.  Cocaine - is commonly self-administered through the nasal membranes (snorted) Drug penetration of the CNS:  Once a drug enters the bloodstream, it is carried to the blood vessels of the central nervous system.  Blood-brain barrier – makes it difficult for many potentially dangerous bloodborne chemicals to pass from the blood vessels of the CNS into the extracellular space around CNS neurons and glia. Drug Action, Metabolism & Elimination. Mechanisms of Drug Action  Psychoactive drugs influence the nervous system in many ways.  Some drugs act diffusely on neural membranes throughout the CNS.  Others in a more specific way ;  binding to particular synaptic receptors; by influencing the synthesis, transport, release, or deactivation of particular neurotransmitters; or by influencing the chain of chemical reactions elicited in postsynaptic neurons. Drug Metabolism & Elimination  The actions of most drugs are terminated by enzymes synthesized by the liver. Drug Action, Metabolism & Elimination.  These liver enzymes stimulate the conversion of active drugs to nonactive forms – drug metabolism.  Drug metabolism - eliminates a drug’s ability to pass through lipid membranes of cells so that it can no longer penetrate the bloodbrain barrier.  Other than that, small amounts of some psychoactive drugs are passed from the body in urine, sweat, feces, breath, and mother’s milk. Drug Tolerance Drug Tolerance  a state of decreased sensitivity to a drug that develops as a result of exposure to it.  Can be demonstrated in two ways – showing that a given dose of the drug has less effect than it had before drug exposure or showing that it takes more of the drug to produce the same effect.  A shift in the dose-response curve  3 important points to remember:  One drug can produce tolerance to other drugs that act by the same mechanism; this is known as cross tolerance.  Drug tolerance often develops to some effects of a drug but not to others.- Because they have become tolerant to some effects of a drug they are tolerant to all of them (x). Tolerance may develop to some effects of a drug while sensitivity to other effects of the same drug increases. – drug sensitization.  Drug tolerance is not a unitary phenomenon - there is no single mechanism that underlies all examples of it  Withdrawal syndrome – Drug Withdrawal Effects & Physical Dependence  After significant amounts of a drug have been in the body for a period of time (e.g., several days), its sudden elimination can trigger an adverse physiological reaction.  Effects of drug withdrawal are virtually always opposite to the initial effects of the drug.  E.g; withdrawal of anticonvulsant drugs often triggers convulsions, and the withdrawal of sleeping pills often produces insomnia.  Physical dependent – individuals who suffer withdrawal reactions when they stop taking a drug.  Withdrawal effects may be produced by the same neural changes that produce drug tolerance. Withdrawal Theory • The fact that withdrawal effects are frequently opposite to the initial effects of the drug suggests that withdrawal effects may be produced by the same neural changes that produce drug tolerance • Exposure to a drug produces compensatory changes in the nervous system that offset the drug’s effects and produce tolerance. • When the drug is eliminated from the body, these compensatory neural changes - manifest themselves as withdrawal symptoms that are opposite to the initial effects of the drug.  Drug addicted individuals are habitual drug users, but not all habitual drug users are drug-addicted individual. Drug Addiction  Drug addicted individuals - habitual drug users who continue to use a drug despite its adverse effects on their health & social life, and despite their repeated efforts to stop using it.  Addicted individuals sometimes take drugs to prevent or alleviate their withdrawal symptoms – not major factor.  Tobacco  When a cigarette is smoked, nicotine—the major psychoactive ingredient of tobacco referred to as tar, are absorbed through the lungs.  Nicotine acts on nicotinic cholinergic receptors in the brain  Alcohol 5 Commonly used Drugs  Alcohol molecules are small and soluble in both fat and water, they invade all parts of the body.  classified as a depressant because at moderate-to-high doses it depresses neural firing; however, at low doses, it can stimulate neural firing and facilitate social interaction  alcohol drinker experiences various degrees of cognitive, perceptual, verbal, and motor impairment, as well as a loss of control that can lead to a variety of socially unacceptable actions.  Marijuana  Marijuana is the name commonly given to the dried flower buds of Cannabis.  Cocaine & other stimulants.  Marijuana is the name commonly given to the dried flower buds of Cannabis  crack, a potent, cheap, smokeable form of cocaine.  Opiods: Heroin & Morphine  Morphine, codeine, and other drugs that have similar structures or effects are commonly referred to as opioids.  The opioids exert their effects by binding to receptors whose normal function is to bind to endogenous opioids.  The opioids have a Jekyll-and-Hyde character. On their Dr. Jekyll side, the opioids are effective as analgesics (painkillers) they are also extremely effective in the treatment of cough and diarrhea. But, unfortunately, the kindly Dr. Jekyll brings with him the evil Mr. Hyde—the risk of addiction.  Slows brain activity  Strains liver Physiological Effects of Substance Abuse  Slows reflexes (some may increase reflexes) Short Term Effects  Dizziness  Loss of inhibition  High or happy feeling  Depression or mood swings  Faster pulse rate  Loss of appetite Physiological Effects of Substance Abuse Long Term Effects            Impaired memory Menstrual irregularities Impotence Kidney damage Lung problems Risk of damage to fetus Brain damage Heart damage Liver damage Growth impairment Possible birth defects  Non-use  Never used a particular drug  Experimental Use  Has tried a substance once or several times  Use is motivated by curiosity about the drug effect, and peer influence  Occasional Use Drug Use Continuum  Use is frequent and irregular, usually confined to special occasions  Availability, accessibility, and affordability influence use  Regular Use  Use has a predictable pattern, which may entail frequent or infrequent use  Usually the user feels in control of the drug use  Dependence Use     Use is regular and predictable and usually frequent The user experiences a physiological and/or psychological need for the drug User will continue to use despite the consequences Drugs are often used alone and daily activities may be planned around drug use.